System and method for monitoring eye movement

ABSTRACT

Apparatus for monitoring movement of a person&#39;s eye, e.g., to monitor drowsiness. The system includes a frame that is worn on a person&#39;s head, an array of emitters on the frame for directing light towards the person&#39;s eye, and an array of sensors on the frame for detecting light from the array of emitters. The sensors detect light that is reflected off of respective portions of the eye or its eyelid, thereby producing output signals indicating when the respective portions of the eye is covered by the eyelid. The emitters project a reference frame towards the eye, and a camera on the frame monitors movement of the eye relative to the reference frame. This movement may be correlated with the signals from the array of sensors and/or with signals from other sensors on the frame to monitor the person&#39;s level of drowsiness.

Notice: More than one reissue application has been filed for the reissueof U.S. Pat. No. 6,163,281. The reissue applications are applicationSer. No. 11/097,942, issued as Re 39,539, Ser. No. 11/732,828, which isa continuation reissue of Re 39,539, and Ser. No. 12/199,693 (thepresent application), which is a divisional reissue of Ser. No.11/732,828.

This application is a reissue of U.S. Pat. No. 6,542,081 and is adivisional of application Ser. No. 11/732,828, which is a continuationof application Ser. No. 11/097,942, issued as Re 39,539, which are bothreissues of application Ser. No. 09/740,738, U.S. Pat. No. 6,542,081,which is a continuation-in-part of application Ser. No. 09/104,258,filed Jun. 24, 1998, issuing as U.S. Pat. No. 6,163,281 on Dec. 19,2000, which is a continuation-in-part of application Ser. No.08/978,100, filed Nov. 25, 1997, now U.S. Pat. No. 6,246,344 issued Jun.12, 2001, which is a continuation-in-part of application Ser. No.08/699,670, filed Aug. 19, 1996, now U.S. Pat. No. 5,748,113 issued May5, 1998, the disclosures of which are expressly incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates generally to systems and methods formonitoring movement of a human eye, and more particularly to systems andmethods for real-time monitoring of fatigue and other states of mind inindividuals, purposeful communication, and/or controlling devices basedupon movement of their eye, eyelid, and/or other components of theireye.

BACKGROUND

There have been attempts to use movement of the human eye to monitorinvoluntary conditions, specifically a person's wakefulness ordrowsiness. For example, U.S. Pat. No. 3,863,243 discloses a device thatsounds an alarm to warn a person using the device that they arebeginning to fall asleep. The device includes a frame similar to a setof eyeglasses onto which is mounted a fiber optic bundle and a photocellthat are directed towards the user's eye when the frame is worn. Thefiber optic bundle is coupled to a source of light and a pulse generatorto emit light towards the user's eye.

The photocell detects the intensity of light reflected off of the user'seye, i.e., either by the eyelid when the eye is closed or the eyesurface when the eye is open. Circuitry receives a signal from thephotocell, and uses a timer to distinguish between regular blinks, andan extended time period during which the eye is closed, i.e., a timeperiod that may indicate that the person is falling asleep. When athreshold time elapses, an alarm is sounded to notify and/or wake theuser. This device, however, requires running wires and fiber opticbundles from the frame to external components, e.g., the pulse generatorand the required circuitry, and for this reason, the device may beawkward or inconvenient to use.

Other devices, such as those disclosed in U.S. Pat. Nos. 5,469,143 and4,359,724, directly engage the eyelid or eyebrow of a user to detectmovement of the eye and activate an alarm when a drowsiness condition isdetected. These mechanical devices may be mounted directly onto the skinto detect muscle movement or may involve placing a mechanical armagainst the eyelid, and consequently may be uncomfortable to wear anduse.

In addition, some devices may detect eye movement, but may not be ableto distinguish when the eye is opened or closed. For example, it may bedesirable to measure the percentage of total time that the eyelids areclosed as a function of time or the area of the palpebral fissure thatis covered by the eyelid as the eye is opened or closed, commonly knownas “PERCLOS,” for example during medical research or when monitoringdriver alertness. Devices that merely detect eye muscle movement oreyelash movement may not be able to distinguish when the eye is open orclosed, and consequently may not be able to measure PERCLOS. Similarly,such devices may not measure other parameters, such as velocity ofeyelid closing or opening, acceleration or deceleration characteristics,duration of open or closed eye states, intervals between eye blinksand/or partial versus full eye blinks or eye closures.

Further, infrared cameras or other devices may be used to monitor adriver's awareness, which are typically mounted on the dashboard, roofor other fixed mounting within the user's vehicle. Such devices,however, require that the user maintain constant eye contact with thecamera. In addition, they do not monitor eyelid movement if the userlooks sideways or downwards, turns around, exits the vehicle orcompartment in which he or she is being monitored, or if the cameramoves relative to the individual. Further, such cameras may haveproblems seeing through eyeglasses, sunglasses, or even contact lenses,and may not operate effectively in sunlight.

Accordingly, it is believed that a more effective system and method formonitoring eye and/or eyelid movement would be considered useful.

SUMMARY OF THE INVENTION

The present invention is directed to systems and methods for monitoringeye movement. Generally, humans blink at least about 5-30 times perminute, or about 7,000-43,000 times per day. Each involuntary-reflexiveblink lasts about 200-300 milliseconds, and generally averaging about250 milliseconds, amounting to about 1,750-10,800 seconds per day of eyeclosure due to involuntary blinking. As tiredness or sleepiness occurs,the eye blink gets longer and slower until the eyes begin to close forshort term “microsleeps,” i.e., sleep conditions that last for about 3-5seconds or longer, or for prolonged sleep. The present inventionprovides systems and methods for monitoring, measuring, and/orresponding to eye movement, e.g., nonpurposeful reflexive eyeblinks.

In a preferred embodiment, the system includes an emitter and a sensorin a predetermined relationship with an eye such that the emitter emitslight and the sensor detects light from the emitter, the sensorproducing a light intensity signal indicating when the eye is open orclosed. More preferably, the emitter is directed or aimed at the eyelidand eye, while the sensor detects eyelid-reflected light, since, unlikethe eyelid, the eye ball (except the retina, which may cause a “redreflex” under white light conditions or “white pupil” under infraredlight) does not reflect substantial light back to the sensor. Circuitryis coupled to the sensor for converting sequential light intensitysignals corresponding to eyelid movement received from the sensor into astream of data, and a processor converts the stream of data into anunderstandable message.

The circuitry for converting sequential light intensity signals maycompare the sequential light intensity signals with a predetermined timethreshold to detect voluntary-intentional or unintentional-involuntarysequences of eyelid movements, corresponding, for example, to apredetermined binary code. Memory circuitry may be coupled to theprocessor for storing the stream of data and/or a communication device,such as a video monitor or synthesized voice module, may be coupled tothe processor for communicating the understandable message. In addition,a control system may be coupled to the processor, and the understandablemessage may include a command for controlling equipment, includingelectrical or electronic equipment, machinery, or a computer or computeraccessory devices coupled to the control system.

The system preferably also includes a transmitter, preferably a radiofrequency transmitter, for wireless transmission of the stream of datato a remote location. Alternatively, other forms of wirelesstransmission, e.g. infrared, as well as hard-wire connections may beused. The processor, as well as the memory circuitry, communicationdevice, and/or control system, may be located at the remote location,and a receiver may be coupled to the processor for receiving the streamof data from the transmitter.

In a preferred form, the system includes a detection device having aframe adapted to be worn on a person's head, e.g., with the frameresting on the bridge of the user's nose and/or ears. The frame has theemitter and sensor thereon such that the emitter and sensor are orientedtowards the person's eye when the frame is worn on the person's head.Preferably, the emitter and sensor are a single solid state device, suchas a biosensor device, that emits light within a predetermined frequencyrange, for example infrared light, towards the eye and detects theemitted light reflected off of the eyelid, respectively.

In another preferred embodiment, a system for monitoring a blinkingcycle of a person from a remote location is provided that includes anemitter for directing light towards an eye, and a sensor in apredetermined relationship with the emitter for detecting the emittedlight reflected off of the eye, the sensor producing an output signalindicating when the eye is open or closed. Depending upon the relativeposition of the emitter and sensor with respect to the moving eyelid,the emitter light may be reflected off of the eyelid back to the sensor,or diffused by the surface of the eyeball.

A transmitter is coupled to the sensor for wireless transmission of theoutput signal, and a processor is provided for comparing the outputsignal to a predetermined threshold to detect when the eyelid is closedfor a minimum predetermined duration. A warning indicator may be coupledto the processor, the warning indicator being activated when theprocessor detects that the eyelid is closed for the minimumpredetermined duration. For example, the warning indicator may be anaudible buzzer, a visible warning light, a vibrating device, anelectrical shock device, a gustatory smell device, or other device thatmay act as a stimulus to any sensory modality.

Similar to the previous embodiment, a receiver may be provided at theremote location coupled to the processor for receiving the wirelesstransmission from the transmitter. Memory circuitry may be provided forstoring the output signal and/or a processor may be provided forconverting the output signal into an understandable message. Acommunication device may be coupled to the processor for communicatingthe understandable message.

In another preferred embodiment, a self-contained device for detectingmovement of a person's eyelid is provided that includes a frame adaptedto be worn on the person's head, an emitter on the frame for directinglight towards an eye of the person when the frame is worn, and a sensoron the frame for detecting light from the emitter. The sensor producesan output signal indicating when the eye is open or closed, and atransmitter on the frame is coupled to the sensor for wirelesstransmission of the output signal to a remote location. The frame mayalso include a processor for comparing the output signal to apredetermined threshold to detect drowsiness-induced eyelid movement.Similar to the previous embodiments, the emitter and sensor arepreferably a solid state biosensor device for emitting and detectinginfrared light, or alternatively an array of emitters and/or sensors ina predetermined configuration on the frame, e.g., in a vertical,horizontal, diagonal, or other linear or other geometric array of morethan one emitter and/or sensor oriented towards one or both eyes. Inparticular, an array of emitters and/or sensors allows measurement ofeyelid velocity, acceleration and deceleration, and calculation of“PERCLOS.”

The emitter and/or sensors may be affixed to any number of points on theframe, e.g., around the lens and preferably in the nose bridge, oralternatively anywhere along the frame, including near or on the nasalportion of the frame, the attachment of a temple piece of the frame,and/or surface mounted on the lens of an eyeglass. Alternatively, theemitter and/or sensor may be embedded in the lens of an eyeglass, orotherwise such that they operate through the lens. Thus, the emitter(s)and/or sensor(s) are fixed on an eye-frame such that they move with thewearer's head movements, and continuously focus on the user's eyes,whether the user is in a vehicle, outdoors or in any other environment.

Thus, a system in accordance with the present invention may detecteyelid movement of the user, distinguish normal blinks from othervoluntary or involuntary eyelid movement, and produce a stream of data.The stream of data may be converted into an understandable message, suchas a binary code, a command for controlling a piece of equipment, or anindicator of the user's physical, mental or emotional state. Thus, thesystem may provide a convenient and/or effective method for voluntary orinvoluntary communication based simply upon movement of the user's eye.

In accordance with another aspect of the present invention, a system isprovided for monitoring movement of a person's eye. The system includesa device configured to be worn on a person's head and an array ofemitters on the device for directing light towards an eye of the personwhen the device is worn. The array of emitters is configured forprojecting a reference frame towards the eye. A camera is orientedtowards the eye for monitoring movement of the eye relative to thereference frame. The camera may be provided on the device or may beprovided remote from the device, but in relatively close proximity tothe user.

Preferably, the array of emitters includes a plurality of emittersdisposed in a substantially vertical arrangement on the device, and aplurality of emitters disposed in a substantially horizontal arrangementon the device. Thus, the array of emitters may project a focused set ofcrossed bands towards the eye for dividing a region including the eyeinto four quadrants.

In addition, the system preferably includes one or more scanning ornonscanning sensors on the device for detecting light from the array ofemitters. The one or more sensors produce an output signal indicatingwhen the eye is open or closed, similar to the embodiments describedabove. More preferably, the sensors include an array of focused sensorsin a predetermined relationship with the array of focused emitters fordetecting light from the array of emitters that is reflected off ofrespective portions of the eye or its eyelid. The emitters, because oftheir fixed position, produce a fixed reflection off of the surface ofthe eye and eyelid, appearing as a “glint,” i.e., a spot or band oflight. Each sensor produces an output signal indicating when therespective portion of the eye is covered or not covered by the eyelid.

The system may also include a processor for correlating the outputsignal from the one or more sensors with a video signal from the camerafor determining the person's level of alertness. The system may alsoinclude a warning indicator on the device, the warning indicator beingactivated when the processor determines a predetermined level ofdrowsiness has occurred.

Light from the array of emitters may be emitted towards the eye of auser wearing the device to project a reference frame onto the eye. Thecamera is capable of imaging light produced by the emitters, e.g., inthe infrared light range, thereby detecting the projected light as aspot of light, band of light or other “glint.” Movement of the eyerelative to the reference frame may be monitored with the camera. Agraphical output of the movement monitored by the camera relative to thereference frame may be monitored. For example, infrared light from theemitters may be reflected off of the retina as a “red reflex” underwhite light, as a “white pupil” under infrared light, or as a dark pupilunder subtraction, using methods known to those skilled in the art. Theprocessor, using these methods, may detect movement of the eye's pupilmay be measured relative to the reference frame. This movement may begraphically displayed, showing the movement of the eye's pupil relativeto the reference frame.

In addition, the output signal from the one or more sensors may becorrelated with video signals produced by the camera monitoring movementof the eye relative to the reference frame, thereby determining theperson's level of drowsiness.

Other objects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a patient in a hospital wearing a systemfor communication using eyelid movement in accordance with the presentinvention.

FIG. 2 is an enlarged perspective view of a preferred embodiment of thesystem for communication using eyelid movement, shown in FIG. 1,including a detection device and a processing box.

FIG. 3 is a schematic drawing of a preferred embodiment of circuitry fortransmitting an output signal corresponding to a sequence of eyelidmovements.

FIG. 4 is a schematic drawing of a preferred embodiment of circuitry forcontrolling equipment in response to an output signal corresponding to asequence of eyelid movements.

FIG. 5 is a schematic drawing of a preferred embodiment of circuitry fordetecting eyelid movement.

FIGS. 6A-6C are sectional and front views of alternate embodiments of adevice for emitting light towards and detecting light reflected from asurface of an open eye.

FIGS. 7A-7C are sectional and front views of the devices of FIGS. 6A-6C,respectively, emitting light towards and detecting light reflected froma closed eyelid.

FIG. 8 is a perspective view and block diagram of another preferredembodiment of a system for communication using eyelid movement.

FIG. 9 is a block diagram of the components of a system forcommunication in accordance with the present invention.

FIG. 10A is a perspective view of still another preferred embodiment ofa system for communication using eyelid movement.

FIG. 10B is a schematic detail of a portion of the system of FIG. 10A.

FIG. 10C is a detail of a preferred embodiment of an array of emittersand sensors that may be provided on a nose bridge of an eye frame, suchas that of FIG. 10A.

FIG. 10D is a sectional view of the array of emitters and sensors ofFIG. 10C emitting light and detecting light reflected from an eye.

FIG. 11A is a schematic view of a system for selectively controlling anumber of devices from a remote location based upon eyelid movement.

FIG. 11B is a schematic view of additional devices that may becontrolled by the system of FIG. 11B.

FIG. 12A is a table showing the relationship between the activation ofan array of sensors, such as that shown in FIGS. 10A-10D and an eyebeing monitored by the array, as the eye progresses between open andclosed conditions.

FIG. 12B is a graph showing a stream of data provided by an array ofsensors, such as that shown in FIGS. 10A-10D, indicating the percentageof eye coverage as a function of time (“PERCLOS”).

FIG. 12C is a graphical display of a number of physiological parameters,including PERCLOS, of a person being monitored by a system including adevice such as that shown in FIGS. 10A-10D.

FIG. 12D is a table showing the relationship between the activation oftwo-dimensional arrays of sensors and an eye being monitored, as the eyeprogresses between open and closed conditions.

FIG. 13 is a perspective view of another system for monitoring eyemovement, in accordance with the present invention.

FIG. 14 is a detail of a camera on the frame of FIG. 13.

FIGS. 15A-15I are graphical displays of several parameters that may bemonitored with the system of FIG. 13.

FIG. 16 is a detail of video output from a camera on the frame of FIG.13.

FIG. 17 is a schematic showing circuitry for processing signals from afive-element sensor array, in accordance with an exemplary embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, FIG. 1 shows a patient 10 in a bed 12wearing a detection device 30 for detecting eyelid movement of thepatient 10 to provide voluntary-purposeful and/orinvoluntary-nonpurposeful communication. The detection device 30 iscoupled to a processing box 130 which converts the detected eyelidmovement into a stream of data, an understandable message and/or intoinformation, which may be communicated, for example, using a videodisplay 50, to a medical care provider 40. The detection device 30 andprocessing box 130 together provide a system for communication 14 inaccordance with one aspect of the present invention.

Turning to FIGS. 2, 6A and 7A, a preferred embodiment of a system forcommunication 14 is shown that includes an aimable and focusabledetection device 30 that is attachable to a conventional pair ofeyeglasses 20. The eyeglasses 20 include a pair of lenses 21 attached toa frame 22, which includes bridgework 24 extending between the lenses21, and side members or temple pieces 25 carrying ear pieces 26, all ofwhich are conventional. Alternatively, because the lenses 21 are notnecessary to the present invention, the frame 22 may also be providedwithout the lenses 21.

The detection device 30 includes a clamp 27 for attaching to one of theside members 25 and an adjustable arm 31 onto which is mounted anemitter 32 and a sensor 33. Preferably, the emitter 32 and sensor 33 aremounted in a predetermined relationship such that the emitter 32 mayemit a signal towards an eye 300 of a person wearing the eyeglasses 20and the sensor 33 may detect the signal reflected from the surface ofthe eye 300 and eyelid 302. As shown in FIGS. 6A and 7A, the emitter 32and sensor 33 may be mounted adjacent one another.

Alternatively, as shown in FIGS. 6B and 7B, the emitter 32′ and sensor33′ may be mounted on the frame separately away from one another,preferably such that the emitter 32′ and sensor 33′ are disposedsubstantially laterally with respect to each other. In a furtheralternative, shown in FIGS. 6C and 7C, the emitter 32″ and sensor 33″may be mounted across the eye 300 in axial alignment with another. Asthe eyelid 302 closes, it may break the beam 340 being detected by thesensor 33″.

In a preferred form, the emitter 32 and sensor 33 produce and detectcontinuous or pulsed light, respectively, preferably within the infraredrange to minimize distraction or interference with the wearer's normalvision. Preferably, the emitter 32 emits light in pulses at apredetermined frequency and the sensor 33 is configured to detect lightpulses at the predetermined frequency. This pulsed operation may reduceenergy consumption by the emitter 32 and/or may minimize interferencewith other light sources. Alternatively, other predetermined frequencyranges of light beyond or within the visible spectrum, such asultraviolet light, or other forms of energy, such as radio waves, sonicwaves and the like, may be used.

The processing box 130 is coupled to the detection device 30 by a cable34 including one or more wires therein (not shown). As shown in FIG. 9,the processing box 130 preferably includes a central processing unit(CPU) 140 and/or other circuitry, such as the exemplary circuitry shownin FIGS. 3-5, for receiving and/or processing an output signal 142, suchas a light intensity signal, from the sensor 33. The processing box 130may also include control circuitry 141 for controlling the emitter 32and/or the sensor 33, or the CPU 140 may include internal controlcircuitry.

For example, in a preferred form, the control circuitry 141 controls theemitter 32 to produce a flickering infrared signal pulsed at apredetermined frequency, as high as thousands of pulses per second to aslittle as about 4-5 pulses per second, and preferably at least about5-20 pulses per second, thereby facilitating detection of nonpurposefulor purposeful eye-blinks as short as about 200 milliseconds per blink.The sensor 33 may be controlled to detect light pulses only at thepredetermined frequency specific to the flicker frequency of the emitter32. Thus, by synchronizing the emitter 32 and the sensor 33 to thepredetermined frequency, the system 10 may be used under a variety ofambient conditions without the output signal 142 being substantiallyaffected by, for example, bright sun light, total darkness, ambientinfrared light backgrounds, or other emitters operating at differentflicker frequencies. The flicker frequency may be adjusted to maximizethe efficient measurement of the number of eye blinks per unit time(e.g. about ten to about twenty eye blinks per minute), the duration ofeach eye blink (e.g. about 200 milliseconds to about 300 milliseconds),and/or PERCLOS (i.e., the percentage of time that the eyelid iscompletely or partially closed), or to maximize efficiency of thesystem, while keeping power consumption to a minimum.

The control circuitry 141 and/or processing box 130 may include manualcontrols (not shown) for adjusting the frequency, focus, or intensity ofthe light emitted by the emitter 32, to turn the emitter 32 off and on,to adjust the threshold sensitivity of the sensor 33, and/or to allowfor self-focusing with maximal infrared reflection off of a closedeyelid, as will be appreciated by those skilled in the art.

In addition, the processing box 130 also preferably includes a powersource 160 for providing power to the emitter 32, the sensor 33, the CPU144, and/or other components in the processing box 130. The processorbox 130 may be powered by a conventional DC battery, e.g., a nine voltbattery or a lithium battery. Alternatively, an adapter (not shown) maybe connected to the processor box 130, such as a conventional AC adapteror a twelve volt automobile lighter adapter.

Preferably, the CPU 140 includes timer circuitry 146 for comparing thelength of individual elements of the output signal 142 to apredetermined threshold to distinguish between normal blinks and othereyelid movement. The timer circuitry 146 may be separate discretecomponents or may be provided internally within the CPU 140, as will beappreciated by those skilled in the art. The CPU 140 converts the outputsignal 142 into a stream of data 144 which may be used to communicate toother persons or equipment. For example, the stream of data 144 producedby the CPU 140 may be a binary signal, such as Morse code or ASCI code.Alternatively, the CPU 140 may be capable of producing a synthesizedvoice signal, a control signal for a piece of equipment, or even apictorial representation.

To facilitate communication, the processing box 130 may include avariety of output devices for using the stream of data 144. For example,an internal speaker 150 may be provided, which may produce an alarmsound or a synthesized voice. An output port 148 may be provided towhich a variety of equipment, such as the video display 50 shown in FIG.1, may be directly coupled by hard-wire connections.

The processing box 130 may also include a transmitter 152 coupled to theCPU 144 for wireless communication of the stream of data 144 to a remotelocation. For example, as shown in FIG. 9, the system for communication14 may also include a receiving and processing unit 154, such as acomputer or other control or display system. The transmitter 152 ispreferably a radio frequency transmitter capable of producing a shortrange signal, for example, reaching as far as about one hundred feet ormore, and preferably about forty five feet to fifty feet, even throughwalls or obstacles, although alternatively an infrared transmitter mayalso be effective.

The transmitter 152 may also be coupled to an amplifier (not shown) toallow the stream of data to be transmitted thousands of feet or more.For example, the amplifier and transmitter 152 may communicate viatelephone communication lines, satellites and the like, to transmit thestream of data to a remote location miles away from the system. Thesystem may include, or may be coupled to a global positioning system(GPS) for monitoring the location, movement, and state of wakefulnessand safety of an individual wearing the detection device 30.

The receiving and processing unit 154 includes a receiver 156,preferably a radio frequency receiver, for receiving a signal 153,including the stream of data, transmitted by the transmitter 152. Aprocessor 158 is coupled to the receiver 156 for translating, storingand/or using the information in the stream of data, the processor 158being coupled to memory circuitry 160, a communication device 162,and/or a control system 164. For example, the receiving and processingunit 154 may include the memory circuitry 160 therein into which theprocessor 158 may simply store the stream of data for subsequentretrieval and analysis.

The processor 158 may interpret the stream of data, for example, byconverting a binary code in the stream of data into an understandablemessage, i.e., a series of letters, words and/or commands, and/or mayuse augmentative communication devices or software (such as KE:NX orWords Plus) to facilitate communication. The resulting message may bedisplayed on the communication device 162, which may include a videodisplay for displaying text, pictures and/or symbols, a synthesizedvoice module for providing electronic speech, and the like.

Alternatively, the stream of data may be displayed graphically on acomputer of video screen or other electronic display device as a “realtime” message signal or numerically (e.g., displaying blink rate, blinkduration, PERCLOS, etc.), or displayed graphically similar to an EKG orEEG tracing. In addition, as shown in FIG. 12C, the stream of data maybe displayed along with other physiological data (e.g. heart rate,respiratory rate, other sleep polysomnographic (PSG) orelectroencephalographic (EEG) variables). Alternatively, the stream ofdata may be integrated with controllers which monitor automobile ormechanical functions (e.g. vehicle speed, acceleration, brakingfunctions, torque, sway or tilt, engine or motor speed, etc.) to makeintelligent decisions regarding slowing down or speeding up the vehicledepending upon road and/or vehicle conditions, as well as the state ofconsciousness, wakefulness or attentiveness of the driver or machineoperator.

In addition, the message may be interpreted by the processor 158 fordirecting the control system 164 to control one or more pieces ofmachinery or equipment. For example, the stream of data may include acommand to direct the control system 164 to control relay switches orother devices to turn off and on an electrical device, such as anappliance, electrical wheelchair, engine, light, alarm, telephone,television, computer, a tactile vibrating seat, and the like, or tooperate an eye-activated computer mouse or other controller.

Alternatively, the processor 158 may use the stream of data to controlPC, IBM, Macintosh and other computers and compatible computer softwareand/or hardware, e.g., to interact with a computer similar to a mouse, a“return” key or a “joystick.” For example, the stream of data mayinclude commands to activate a series of menus from which sub-menus orindividual items may be selected, as are used in commercially availablespecial communications software, such as WORDS-PLUS or Ke:NX. Theprocessor 158 may then control, scroll or select items from computersoftware programs, operate a printer or other peripheral device (e.g.,selecting a font, paragraph, tab or other symbol operator, selectingcommands, such as “edit,” “find,” “format,” “insert,” “help,” orcontrolling CD-ROM or disc drive operations, and/or other Windows andnon-Windows functions).

Alternatively, the receiver 156 may be coupled directly to a variety ofdevices (not shown), such as radio or television controls, lamps, fans,heaters, motors, remote control vehicles, vehicle monitoring orcontrolling devices, computers, printers, telephones, lifeline units,electronic toys, or augmentative communication systems, to provide adirect interface between the user and the devices.

During use, the detection device 30 is placed on a user's head, i.e., byputting the eyeglasses 20 on as shown in FIG. 1. The adjustable arm 31and/or the clamp 27 may be adjusted to optimally orient the emitter 32and sensor 33 towards the user's eye 300 (shown in FIGS. 6A-6C and7A-7C). The emitter 32 is activated and a beam of light 340 is directedfrom the emitter 32 towards the eye 300. The intensity and/or frequencyof the emitter 32 and/or the threshold sensitivity of the sensor 33 orother focus may then be adjusted (e.g. manually or automatically usingself-adjusting features).

Because of the difference in the reflective characteristics of thesurface of the eye 300 itself and the eyelid 302, the intensity of thelight reflected off of the eye 300 depends upon whether the eye 300 isopen or closed. For example, FIGS. 6A and 6B illustrate an open eyecondition, in which a ray of light 340 produced by the emitter 32strikes the surface of the eye 300 itself and consequently is scattered,as shown by the rays 350. Thus, the resulting light intensity detectedby the sensor 33 is relatively low, i.e., the sensor 33 may not receiveany substantial return signal.

In FIGS. 7A and 7B, the eye 300 is shown with the eyelid 302 closed asmay occur during normal blinks, moments of drowsiness, intentionalblinks, or other eyelid movement. Because the light 340 strikes theeyelid 302, it is substantially reflected back to the sensor 33, asshown by the ray 360, resulting in a relatively high light intensitybeing detected by the sensor 33. Alternatively, as shown in 7C, the beamof light 340 may be broken or cut by the eyelid 302 when the eye 300 isclosed.

The sensor 33 consequently produces a light intensity signal thatindicates when the eye 300 is open or closed, i.e., corresponding to thetime during which reflected light is not detected or detected,respectively, by the sensor 33. Generally, the intensity of the infraredlight reflected from the surface of the eyelid is not substantiallyaffected by skin pigmentation. If it is desired to adjust the intensityof light reflected from the eyelid, foil, glitter, reflectivemoisturizer creams and the like may be applied to increase reflectivity,or black eye liner, absorptive or deflective creams and the like may beapplied to reduce reflectivity.

Returning to FIG. 9, the light intensity detected by the sensor 33results in an output signal 142 including a series of time-dependentlight intensity signals (as shown, for example, in FIG. 12B). The outputsignal 142 is received by the CPU 140 coupled to the sensor 33, whichcompares the length of time of each light intensity signal 142, forexample, corresponding to a closed eye condition, with a predeterminedthreshold. The timer circuitry 146 may provide a threshold time to theCPU 140 for distinguishing normal blinks from intentional and/or otherunintentional eyelid movement, which the CPU 140 may then filter out ofthe output signal 142. The CPU 140 then produces a stream of data 144which may be used for voluntary and/or involuntary communication.

In one useful application, the detection device 30 may be used to detectimpending drowsiness or “micro-sleeps” (i.e., sleep intrusions intowakefulness lasting a few seconds) of a user, with the processing box130 triggering a warning to alert the user, others in his or herpresence, or monitoring equipment of the onset of drowsiness. Thethreshold of the timer circuitry 146 may be adjusted such that the CPU140 detects relatively long periods of eye closure, as may occur when aperson is falling asleep.

For example, because normal blinks are relatively short, the thresholdmay be set at a time ranging from close to zero seconds up to severalseconds, preferably from about 200 milliseconds to about 300milliseconds, and most preferably about 250 milliseconds, to distinguishnormal blinks from drowsiness-induced eyelid movement. When the CPU 140detects a drowsiness condition, i.e., detects a high light intensitysignal exceeding the predetermined threshold time, it may activate awarning device. The warning device may be included within the processingbox 130, such as the speaker 150, or alternatively on the frame, forexample, by mounting a warning light (not shown) or an alarm speaker(not shown in FIG. 9, see FIG. 10C) on the frame.

Alternatively, the detection device 30 may be used to unobtrusivelyrecord or monitor drowsiness-induced eyelid movement, with the CPU 140producing a stream of data 144 which the transmitter 152 may transmit tothe receiving and processing unit 154 (FIG. 9). For example, the device30 may be used in conjunction with a vehicle safety system to monitor adriver's level of awareness or attentiveness. The stream of data 144 maybe transmitted to a receiving and processing unit 154 mounted in avehicle, which may store data on the driver's drowsiness and/or may usethe data to make decisions and control the vehicle, e.g., adjust thevehicle's speed or even turn the vehicle's engine off. Thus, thedetection device 30 may be used to monitor truck drivers, taxi drivers,ship or airline pilots, train conductors or engineers, radar or airportcontrol tower operators, operators of heavy equipment or factorymachinery, scuba divers, students, astronauts, entertainmentparticipants or observers, and the like. The signals may be stored andanalyzed in real time for trend changes measured over time to predictdrowsiness effects of individuals using the device.

The detection device 30 and system 14 may also be used in a medicaldiagnostic, therapeutic, research or professional setting to monitor thewakefulness, sleep patterns and/or the effects of drugs, which mayaffect blink rate, blink velocity, blink duration, or PERCLOS of apatient or vehicle operator. Similar to the method just described, theCPU 140 produces a stream of data 144, which the transmitter may send toa remote receiving and processing unit 154, which may store the streamof data 144 in the memory circuitry 160 for later retrieval and analysisby researchers, medical professionals, or safety personnel (e.g.,similar to the way in which flight recorder data may be stored in anaircraft's “black box” recorder). The receiving and processing unit 154may also display the stream of data 144, for example at a nurse'sstation, as an additional parameter to continually monitor a patient'sphysical, mental, or emotional condition. The unit 154 may store and/orproduce a signal, e.g., by a series of algorithms, that must beresponded to within a predetermined time (e.g., performance vigilancemonitoring) to prevent false positives and negatives.

A number of medical conditions may be monitored by the detection device30 and system 14, such as petit mal epilepsy, in which the eyes flutterat a rate of about three cycles per second, grand mal or psychometerseizures, where the eyes may stare or close repetitively in a jerkymanner, myoclonic seizures, in which the lids may open and close in ajerky manner, or tics, or other eye movements, such as encountered bypeople with Tourette's syndrome. The system may be used to monitorg-lock of pilots caused by g-force effects, hypoxemia of passengers orcrew in aircraft due to losses in cabin pressure, nitrogen narcosis or“the bends” in divers, or the effects of gases, chemicals, or biologicalagents on military personnel or other individuals.

The system may also be used to monitor psychological situations, forexample, to detect when a person lies (e.g., by closing their eyes whenlying), during hypnosis, to monitor attentiveness, the effects ofmedications, e.g., L-dopa and other anti-Parkinsonian medications oranti-convulsants, drugs, alcohol, toxins, or the effects of hypoxia orventilation, and the like. Neurological conditions may also be monitoredwhere the innervation or mechanical function of the eyelid may beaffected, such as in Parkinson's disease, muscle diseases, e.g.,myotonia, myotonic muscular dystrophy, blepharospasm, photophobia orlight sensitivity, encephalopathy, seizures, Bell's palsy, or where thecondition may produce eyelid drooping or ptosis, such as third cranialnerve palsy or paresis, brainstem lesions or stroke, tumors, infection,metabolic diseases, trauma, degenerative conditions, e.g., multiplesclerosis, amyotrophic lateral sclerosis, polyneuropathy, myestheniagravis, botulism, tetanus, tetany, tardive dyskinesia, brainstemencephalitis, and other primary eyelid conditions, such as exophthalmos,thyrotoxicosis or other thyroid conditions.

Similarly, the detector device 30 may be used in biofeedbackapplications, for example, in biofeedback, hypnosis or psychologicaltherapies of certain conditions (e.g. tic disorders). The detectordevice 30 may produce a stimulus, e.g. activating a light or speaker,and monitor the user's eyelid movement in anticipation of receiving aresponse, e.g., a specific sequence of blinks, acknowledging thestimulus within a predetermined time. If the user fails to respond, theprocessor may store the response, e.g. including response time, and/ormay automatically transmit a signal, such as an alarm signal.

In addition, the detection device 30 may be used to monitor individualsin non-medical settings, such as during normal activity in a user's homeor elsewhere. For example, individuals with involuntary medicalconditions, such as epilepsy or narcolepsy, may be monitored, or otherindividuals, such as, infants and children, prison inmates, dementedpatients (e.g., with Alzheimer's disease), law enforcement personnel,military personnel, bank tellers, cashiers, casino workers, students,swing or graveyard shift workers, and the like, may be monitored.Similar application may be applied in a sleep laboratory for monitoringsleep patients to measure parameters, such as onset of sleep, sleeplatency, time of eyelid closing or opening, time of awakening during thenight, etc., or to animal research where eye blinking may be a factor tobe studied. Similarly, the performance and vigilance abilities of theuser may be tested and analyzed as a direct function of, or inrelationship to, PERCLOS.

When the CPU 140 detects the presence of particular eyelid movement,such as an extensive period of eye closure which may occur, for example,during an epileptic seizure, a syncopal episode, a narcoleptic episode,or when dozing off while driving or working, the CPU 140 may produce anoutput signal which activates an alarm. Alternatively, the transmitter152 may send an output signal to shut off equipment being used, tonotify medical personnel, such as by automatically activating atelephone to dial emergency services, to signal remote sites, such aspolice stations, ambulances, vehicle control centers, guardians, and thelike.

The system for communication 14 may also find useful application forvoluntary communication. A user wearing the detection device 30 mayintentionally blink in a predetermined pattern, for example, in Morsecode or other blinked code, to communicate an understandable message topeople or equipment (e.g., to announce an emergency). The CPU 140 mayconvert a light intensity signal 142 received from the sensor 33 andcorresponding to the blinked code into a stream of data 144, or possiblydirectly into an understandable message including letters, words and/orcommands.

The stream of data 144 may then be displayed on a video 60 display 50(see FIG. 1) coupled to the output port 148, or emitted as synthesizedspeech on the internal speaker 150. The stream of data 144 may betransmitted by the transmitter 152 via the signal 153 to the receivingand processing unit 154 for displaying messages, or for controllingequipment, such as household devices, connected to the control system164. In addition to residential settings, the system 14 may be used byindividuals in hospitalized or nursing care, for example by intubated,ventilated, restrained, paralyzed or weakened patients, to communicateto attending medical staff and/or to consciously signal a nurse'sstation. These include all patients who have no physical ability tocommunicate verbally, but who retain ability to communicate using eyeblinking of one or both eyes (e.g., patients with amyotrophic lateralsclerosis, transverse myelitis, locked-in syndrome, cerebravascularstrokes, terminal muscular dystrophy and those intubated onventilation).

The device may be used in any environment or domain, e.g., through wateror other substantially transparent fluids. Further, the device 30 mayalso be used as an emergency notification and/or discrete security tool.A person who may be capable of normal speech may wear the device 30 inthe event of circumstances under which normal communication, i.e.,speech, is not a viable option. For example, a bank or retail employeewho is being robbed or is otherwise present during the commission of acrime may be able to discretely blink out a preprogrammed warning tonotify security or to call law enforcement. Alternatively, a person withcertain medical conditions may wear the device in the event that theyare physically incapacitated, i.e., are unable to move to call foremergency medical care, but are still able to voluntarily move theireyes. In such cases, a pre-recorded message or identifying data (e.g.name of the user, their location, the nature of the emergency, etc.) maybe transmitted to a remote location by a specific set of eyeblink codesor preprogrammed message. In this manner, the detection device 30 may beused to monitor patients in an ICU setting, patients on ventilators,prisoners, elderly or disabled persons, heavy equipment operators, truckdrivers, motorists, ship and aircraft pilots, train engineers, radar orairport control tower operators, or as a nonverbal or subliminal toolfor communication by military guards, police bank tellers, cashiers,taxi-drivers, and the like. The detection device 30 may also be used asa recreational device, for example, as a children's toy similar to awalkie-talkie or to operate a remote control toy vehicle.

In addition, it may be desirable to have the CPU 140 perform anadditional threshold comparison to ensure continued use of the detectiondevice 30. For example, additional timer circuitry may be coupled to theCPU 140 such that the CPU 140 may compare the light intensity signalsreceived from the sensor 33 to a second predetermined threshold providedby the timer circuitry. Preferably, the second predetermined thresholdcorresponds to a time period during which a person would normally blink.If the CPU 140 fails to detect a normal blink within this time period orif the user fails to respond to a predetermined stimulus (e.g. ablinking light or sound), the CPU 140 may produce a signal, activatingthe speaker 150 or transmitting a warning using the transmitter 152.

This may be useful, if, for example, the detection device 30 is removedby a perpetrator during commission of a crime, falls off because of theonset of a medical episode, as well as to prevent “false alarms,” or tomeasure the “state of attentiveness” of the user. Alternatively,performance vigilance tasks may be required of the user to determinewhether the signal transmitted is a purposeful or “false alarm” signal,and also for measuring attention or drowsiness levels for purposes ofbiofeedback, and also to measure compliance of the user wearing thedevice.

Alternatively, the polarity of the output signal 142 may be reversedsuch that a stream of data is produced only when the eye is opened, forexample, when monitoring patients in a sleep lab to measure onset ofsleep, sleep latency, time of eyelid closure, etc., or to monitorsleeping prison inmates. For such uses, the CPU 140 may activate analarm only when an open eye condition is detected, as will beappreciated by those skilled in the art.

Turning to FIG. 8, another preferred embodiment of the detection device30 in accordance with the present invention is shown. In thisembodiment, the emitter and sensor are a single solid state lightemission and detecting biosensor device 132 which are mounted directlyonto the eyeglasses 20. The biosensor device 132, which preferablyproduces and detects infrared light, may be as small as 2 mm ×4 mm andweigh only a few grams, thereby enhancing the convenience, comfortand/or discretion of the detection device 30. Because of the small size,the biosensor device 133 may be mounted directly in the lens 21, asshown in FIG. 8, on an outside or inside surface of the lens 21, in thebridgework 24 or at another location on the frame 22 that may facilitatedetection of eye movement. The biosensor device 132 may measure lessthan about five millimeters by five millimeters surface area, and mayweigh as little as about one ounce, thereby providing a emitter/sensorcombination that may be unobtrusive to vision, portable, and may beconveniently incorporated into a light weight eye frame. Because theentire system may be self-contained on the frame, it moves with the userno matter which direction he or she looks and may operate in a varietyof environments or domains, day or night, underwater, etc.

Hamamatsu manufactures a variety of infrared emitter and detectordevices which may be used for the biosensor device 132, such as ModelNos. L1909, L1915-01, L2791-02, L2792-02, L2959, and 5482-11, oralternatively, a Radio Shack infrared emitter, Model No. 274-142, may beused. Multiple element arrays, e.g., linear optical scanning sensorarrays, appropriate for use with the present invention may be availablefrom Texas Advanced Optoelectronic Solutions, Inc. (TAOS) of Plano,Tex,, such as Model Nos. TSL 201 (64 pixels×1 pixel), TSL 202 (128×1),TSL 208 (512×1), TSL 2301 (102×1). These sensors may be used incombination with lens arrays to facilitate focusing of the detectedlight, such as the Selfoc lens array for line scanning applications madeby NSG America, Inc. of Irvine, Calif.

In addition, multiple biosensor devices 132 may be provided on theeyeglasses 20, for example, a pair of biosensor devices 132 may beprovided, as shown in FIG. 8, for detecting eyelid movement of each eyeof the user (not shown). A cable 134 extends from each biosensor device132 to a processing box 130, similar to the processing box 130 describedabove. The CPU 140 of the processing box 130 (not shown in FIG. 8) mayreceive and compare the output signal from each biosensor device 132 tofurther augment distinguishing normal blinks from other eyelid movement.

The pair of biosensor devices 132 may allow use of more sophisticatedcodes by the user, e.g., blinking each eye individually or together, forcommunicating more effectively or conveniently, as will be appreciatedby those skilled in the art. In one form, a blink of one eye couldcorrespond to a “dot,” and the other eye to a “dash” to facilitate useof Morse code. The output signals from each eye could then beinterpreted by the CPU 140 and converted into an understandable message.

In another form, a right eye blink (or series of blinks) may cause anelectric wheelchair to move to the right, a left eye blink (or series ofblinks) may move to the left, two simultaneous right and left eye blinksmay cause the wheelchair to move forward, and/or four simultaneous rightand left eye blinks may cause the wheelchair to move backward. Similarcombinations or sequences of eye blinks may be used to control theon/off function, or volume or channel control of a television, AM/FMradio, VCR, tape recorder or other electronic or electromechanicaldevice, any augmentative communications or controlling device, or anydevice operable by simple “on/off” switches (e.g., wireless televisionremote controls single switch television control units, universal remotecontrollers, single switch multi-appliance units with AC plug/walloutlet or wall switch modules, computer input adapters, lightedsignaling buzzer or vibrating signal boxes, switch modules of all types,video game entertainment controller switch modules and switch-controlledelectronic toys).

In additional alternatives, one or more lenses or filters may beprovided for controlling the light emitted and/or detected by thebiosensor device, an individual emitter and/or detector. For example,the angle of the light emitted may be changed with a prism or otherlens, or the light may be columnated or focused through a slit to createa predetermined shaped beam of light directed at the eye or to receivethe reflected light by the sensor. An array of lenses may be providedthat are adjustable to control the shape, e.g. the width, etc., of thebeam of light emitted or to adjust the sensitivity of the sensor. Thelenses may be encased along with the emitter in plastic and the like, orprovided as a separate attachment, as will be appreciated by thoseskilled in the art.

Turning now to FIG. 10A, another preferred embodiment of a system forcommunication 414 is shown, that includes a frame 422 including abiosensor device 432 with associated processor and transmitter circuitry430 provided directly on the frame 422, for example, to enhance theconvenience and discretion of the system for communication 414. Theframe 422 may include a bridge piece 424 onto which the biosensor device432 may be slidably and/or adjustably mounted, and a pair of earsupports 423, 425.

One of the supports 423 may have a larger size compared to the othersupport 425, for example, to receive the processor and transmittercircuitry 430 embedded or otherwise mounted thereon. A processor 440,similar to the CPU 140 in the processing box 130 previously described,may be provided on the frame 422, and a power source, such as a lithiumbattery 460, may be inserted or affixed to the support 423. A radiofrequency or other transmitter 452 is provided on the support 423,including an antenna 453, which may be embedded or otherwise fastenedalong the ear support 423, in the temple piece or elsewhere in the frame422.

The system 414 may also include manual controls (not shown) on the earsupport 423 or elsewhere on the frame 422, for example to turn the poweroff and on, or to adjust the intensity and/or threshold of the biosensordevice 432. Thus, a system for communication 414 may be provided that issubstantially self-contained on the frame 422, which may or may notinclude lenses (not shown) similar to eyeglasses. External cables orwires may be eliminated, thereby providing a more convenient andcomfortable system for communication.

In another alternative, shown in FIGS. 10B, 10C, and 10D, a linear array530 of emitters 532 and sensors 533 may be provided, preferably in avertical arrangement mounted on a nose bridge 524 of an eye frame 522. ACPU 540, battery 460, transmitter antenna 543, and warning indicator 550may also be provided on the frame 522, preferably in the temple piece525, similar to the previously described embodiment. An LED 542 orsimilar stimulus device may also be provided at a predetermined locationon the eye frame 522 to allow routine biofeedback responses from theuser. In addition, a receiver 544 may be provided for receiving thestream of data created by the CPU 540 and transmitted by the transmitter543.

As shown particularly in FIG. 10C, each of the sensors 533 and theemitter 532 are coupled to the CPU 540 or other control circuitry forcontrolling the emitter 532 and for processing the light intensitysignals produced by the sensors 532. Thus, the CPU 540 may cycle throughthe sensors 533 in the array 530 and sequentially process the signalfrom each of the sensors 533, similar to the processors previouslydescribed. More preferably, as shown in FIG. 10D, the emitter 532includes a lens 534 to focus a beam of light (indicated by individualrays 360a, 360b) onto the eye 300, preferably towards the pupil 301. Thesensors 533 are embedded within the nose bridge 524 and a slit 535 isprovided for each, the slits 535 having a predetermined size to controlthe reflected light detected by each sensor 533. Thus, each sensor 535may detect movement of the eyelid 302 past a particular portion of theeye 300, e.g., to measure PERCLOS, as shown in FIG. 12A. The sensors oremitters may have lenses or columnating devices to focus emitted orreflected light.

The linear array 530 may facilitate measurement of additional parametersrelated to eyelid movement in addition to mere eye closure. For example,to measure the velocity of the eyelid opening or closing, i.e., the rateof eye closure, the CPU 540 may compare the time delay between theactivation of successive sensors 533. In addition, the output signalsfrom the sensors 553 may be processed to measure the percentage of pupilcoverage of the eyelid 302, for example, due to partial eye closure, asa function of time, e.g., to monitor when the eye is partially, but notcompletely, closed, and/or to monitor the percentage of time that theeye is closed (PERCLOS), as shown in FIGS. 12A-12C, e.g., compared tothe user's baseline of maximal eye opening.

Turning to FIG. 12D, in a further alternative, a two-dimensional arrayof sensors, such as a 5×5 array 633 or a 9×11 array, 733 may beprovided. Other arrays including any number of elements in the array maybe provided, and the invention should not be limited to the exemplaryembodiments described herein. The sensors 633, 733 may then be used tomeasure surface area reflectivity of light from the emitter 632, i.e.,the processor (not shown) may process the signals from each sensor inthe array 633, 733 to create a stream of data indicating the percentageof surface area of the eye 300 covered by the eyelid 302.

The sensors in the array 633, 733 may be sufficiently sensitive or havesufficient resolution such that they may detect “red reflex” or theequivalent infrared “bright pupil” reflection due to the reflection oflight off of the retina through the pupil 301. Thus, the sensors mayproduce a light intensity signal that includes a substantially zerovalue, indicating no red reflex or bright pupil, a low output,indicating red reflex or white pupil reflex, and a high output,indicating reflection off of a closed eyelid 302. The red reflex mayappear as a bright white light pupil (resulting from infrared light fromthe emitter(s) reflecting off of the retina when the eyelid is open, oras a dark or “black pupil” if the processor uses subtraction algorithms,as is known in the art. The processor may thereby process the lightintensity signals to detect when the pupil 301 is covered by the eyelid302, i.e., at which point the user cannot see, even though their eye 300may not be entirely covered by the eyelid 302, generally at a PERCLOSvalue of about 50-75 percent in primary gaze. Alternatively, as theeyelid, eye, and pupil descend, the sensor(s) may detect a red reflex orbright pupil even through the PERCLOS measurement may be as great as 75-80 percent or more, e.g., where the eye may still see through a narrowslit-like palpebral fissure opening in downward gaze.

In another alternative, the processor and/or transmitter circuitry (suchas the CPU 140 in the processor box 130 of FIG. 2, or the CPU's 440, 540of FIGS. 10A and 10B) may include identification circuitry (not shown),either as a discrete memory chip or other circuit element, or within theCPU itself. The identification circuitry may be preprogrammed with afixed identification code, or may be programmable, for example, toinclude selected identification information, such as the identity of theuser, the user's location, an identification code for the individualdetection device, and the like.

The CPU may selectively add the identification information to thetransmitted stream of data 553, or the identification information may beautomatically or periodically included in the stream of data 553,thereby allowing the stream of data 553 to be associated with aparticular detection device, individual user and/or a specific location.The identification information may be used by the processor, forexample, at a remote location, to distinguish between streams of datareceived from a number of detection devices, which may then be stored,displayed, etc. as previously described. Thus, the detection device maynot require users to consciously communicate certain identification orother standard information when the system is used.

As shown in FIG. 11A, the receiver 544 may allow the user to control oneor more devices coupled to the receiver 544 through a single switchmulti-appliance control unit 550. The control unit 550 includes its owntransmitter adapted to transmit on/off or other control signals that maybe received by individual control modules 552a-552fe. The user 10 mayblink to create a transmitted stream of data 553 that includes commandsto turn off and on, or otherwise control, selected appliances using thecontrol unit 550 and control modules 552a-552fe, such as, a radio 554, atelevision 556, a light 558a., a light 562 controlled by a wall switch560, a fan 566 plugged into a wall socket 564, and the like.

Alternatively, as shown in FIG. 11B, the receiver 554 may be coupled toother systems, such as a computer 570 and printer 572, a vehicleintegration system 574, a lifeline unit 576, a GPS or other satellitetransmitter 578, and the like. The transmitted stream of data 553 may beprocessed alone or along with additional data, such as other vehiclesensor information 573, to further enhance monitoring a user, such as along-distance truck driver.

Turning to FIG. 13, yet another embodiment of a system 810 formonitoring eye movement is shown. Generally, the system 810 includes aframe 812 that may include a bridge piece 814 and a pair of ear supports816. The frame 812 may include a pair of lenses (not shown), such asprescription, shaded, or protective lenses, although they are notnecessary for operation of the invention. Alternatively, the system maybe provided on other devices that may be worn on a user's head, such asa pilot's oxygen mask, protective eye gear, a patient's ventilator, ascuba or swimming mask, a helmet, a hat, a head band, a head visor, andthe like (not shown). The components of the system may be provided at avariety of locations on the device that generally minimize interferencewith the user's vision and/or normal use of the device.

An array of emitters 820 are provided on the frame 812, preferably in avertical array 820a and a horizontal array 820b. In a preferredembodiment, the emitters 820 are infrared emitters configured to emitpulses at a predetermined frequency, similar to the embodimentsdescribed above. The emitters 820 are arranged on the frame such thatthey project a reference frame 850 onto the region of the user's eye300. In a preferred embodiment, the reference frame includes a pair ofcrossed bands 850a, 850b dividing the region into four quadrants. Theintersection of the crossed bands is preferably disposed at a locationcorresponding substantially to the eye's pupil during primary gaze,i.e., when the user is looking generally straight forward along axis 310extending directly ahead of the user's eye 300. Alternatively, otherreference frames may be provided, generally including a verticalcomponent and a horizontal component.

An array of sensors 822 are also provided on the frame 812 for detectinglight from the emitters 820 that is reflected off of the user's eyelid.The sensors 822 preferably generate output signals having an intensityidentifying whether the eyelid is closed or open, similar to theembodiments described above. Preferably, the sensors 822 are disposedadjacent to respective emitters 820 for detecting light reflected off ofrespective portions of the eyelid. Alternatively, sensors 822 may onlybe provided in a vertical array, e.g., along the bridge piece 814, formonitoring the amount of eyelid closure, similar to the embodimentsdescribed above. In a further alternative, the emitters 820 and sensors822 may be solid state biosensors (not shown) that provide both theemitting and sensing functions in a single device.

Circuitry may be provided for measuring PERCLOS or other parametersusing the signals generated by the array of sensors. For example, FIG.17 shows an exemplary schematic that may be used for processing signalsfrom a five element array, e.g., to obtain PERCLOS measurements or otheralertness parameters.

Returning to FIG. 13, the system 810 also includes a camera 830 providedon the frame 810. Preferably, the camera 830 is mounted on or adjacentthe bridge piece 814 offset from the axis 310 such that the camera 830is oriented towards the region surrounding one of the user's eyes 300while minimizing interference with the user's vision. The camera 830preferably includes a bundle of fiberoptic cables 832 that terminate ina lens 834, as shown in FIG. 14, on a first end mounted adjacent thebridge piece 814 and a second end 837 that is connected to a detector838, e.g., a CCD or CMOS sensor, such as those used in endoscopes, thatmay convert an image into a digital video signal. The camera 830 isconfigured to detect the frequency of light emitted by the emitters 820,e.g., infrared light. The camera 830 may rely on the light projected bythe emitters 820, or the fiberoptic cables 832 may include emitters 836for projecting light, e.g., infrared light, onto the user's eyes and/orface. In addition, the system 810 may include a second camera 840oriented away from the user's head, e.g., to monitor the user'ssurroundings.

One of the ear supports 816 may include a panel 818 for mounting acontroller or other processor 842, a transmitter 844, an antenna 845,and a battery 846. Preferably, the processor 840 842 is coupled to theemitters 820, the sensors 822, and/or the camera 830 for controllingtheir operation. The transmitter 844 may be coupled to the processor 842for receiving the output signals from the sensors 822 and/or the videosignals from the camera 830, e.g., to transmit the signals to a remotelocation, as described below. Alternatively, the transmitter 844 may becoupled directly to output leads from the sensors 822 and the camera830. The frame 812 may also include manual controls (not shown), e.g.,on the ear support 816, for example, to turn the power off and on, or toadjust the intensity and/or threshold of the emitters 820, the sensors822, and/or the camera 830.

If desired, the system 810 may also include one or more additionalsensors on the frame 812. The sensors may be coupled to the processor842 and/or to the transmitter 844 so that the signals from the sensorsmay be monitored, recorded, and/or transmitted to a remote location. Forexample, one or more position sensors 852a, 852b may be provided, e.g.,for determining the spatial orientation of the frame 812, andconsequently the user's head. For example, actigraphic sensors may beprovided to measure tilt or movement of the head, e.g., to monitorwhether the user's head is drooping forward or tilting to the side.Acoustic sensors, e.g., a microphone 854 may be provided for detectingenvironmental noise or sounds produced by the user.

In addition or alternatively, the frame 812 may include one or moresensors for measuring one or more physical characteristics of the user.For example, EEG electrodes 856 may be provided on the ear support 816,above or below the nasion, and/or other region that may contact thepatient's skin to measure brain activity, e.g., waking, drowsy, or othersleep-related brain activity. An EKG electrode (not shown) may beprovided that is capable of measuring cardiac activity through a skincontact site. A pulse sensor (not shown) may be used to measurecardiovascular pulsations, or an oximetry sensor 858 may be used tomeasure oxygen saturation levels. A thermistor or other sensor maymeasure of respiratory air flow, e.g., through the user's nose. Athermister, thermocouple, or other temperature sensor (not shown) may beprovided for measuring the user's skin temperature. A sweat detector(not shown) may be provided for measuring moisture on the user's skin.

In addition, the system 810 may include one or more feedback devices onthe frame 812. These devices may provide feedback to the user, e.g., toalert and/or wake the user, when a predetermined condition is detected,e.g., a state of drowsiness or lack of consciousness. The feedbackdevices may be coupled to the processor 842, which may control theiractivation. For example, a mechanical vibrator device 860 may beprovided at a location that may contact the user, e.g., on the earsupport 816, that may provide tactile vibrating stimuli through skincontact. An electrode (not shown) may be provided that may producerelatively low power electrical stimuli. A light emitter, such as one ormore LED's may provided at desired locations, e.g., above the bridgepiece 814. Alternatively, audio devices 862, such as a buzzer or otheralarm, may be provided, similar to the previous embodiments. In afurther alternative, aroma-emitters may be provided on the frame 810812, e.g., on or adjacent to the bridge piece 814.

Alternatively, the feedback devices may be provided separate from theframe, but located in a manner capable of providing a feedback responseto the user. For example, audio, visual, tactile (e.g., vibrating seat),or olfactory emitters may be provided in the proximity of the user, suchas any of the devices described above. In a further alternative, heat orcold generating devices may be provided that are capable of producingthermal stimuli to the user, e.g., a remotely controlled fan or airconditioning unit.

The system 810 may also include components that are remote from theframe 812, similar to the embodiments described above. For example, thesystem 810 may include a receiver, a processor, and/or a display (notshown) at a remote location from the frame 812, e.g., in the same room,at a nearby monitoring station, or at a more distant location. Thereceiver may receive signals transmitted by the transmitter 842,including output signals from the sensors 822 or any of the othersensors provided on the frame 812 and/or the video signals from thecamera 830.

A processor may be coupled to the receiver for analyzing signals fromthe components on the frame 812, e.g., to prepare the signals forgraphical display. For example, the processor may prepare the videosignals from the camera 830 for display on a monitor, thereby allowingpersonal monitoring of the user. Simultaneously, other parameters may bedisplayed, either on a single monitor or on separate displays. Forexample, FIG. 15a FIGS. 15A-15I shows signals indicating the output ofvarious sensors that may be on the frame 812, which may be displayedalong a common time axis or otherwise correlated, e.g., to movement ofthe user's eye and/or level of drowsiness. The processor may superimposeor otherwise simultaneously display the video signal in conjunction withthe other sensed parameters to allow a physician or other individual tomonitor and personally correlate these parameters to the user'sbehavior.

In a further alternative, the processor may automatically process thesignals to monitor or study the user's behavior. For example, theprocessor may use the output signals to monitor various parametersrelated to eye movement, such as eye blink duration (EBD), eye blinkfrequency, eye blink velocity, eye blink acceleration, interblinkduration (IBD), PERCLOS, PEROP (percentage eyelid is open), and thelike.

The video signals from the camera 830 may be processed to monitorvarious eye parameters, such as pupillary size, location, e.g., withinthe four quadrant defined by the crossed bands 850, eye trackingmovement, eye gaze distance, and the like. For example, because thecamera 830 is capable of detecting the light emitted by the emitters822, the camera 830 may detect a reference frame projected onto theregion of the user's eye by the emitters. FIG. 16 shows an exemplaryvideo output from a camera included in a system having twenty emittersdisposed in a vertical arrangement. The camera may detect twentydiscrete regions of light arranged as a vertical band. The camera mayalso detect a “glint” point, G, and/or a moving bright pupil, P. Thus,the movement of the pupil may be monitored in relation to the glintpoint, G, and/or in relation to the vertical band 1-20.

Because the emitters 822 are fixed to the frame 812, the reference frame850 remains substantially stationary. Thus, the processor may determinethe location of the pupil in terms of orthogonal coordinates (e.g., x-yor angle-radius) relative to the reference frame 850. Alternatively, ifthe reference frame is eliminated, the location of the pupil may bedetermined relative to any stationary “glint” point on the user's eye.For example, the camera 830 itself may project a point of light onto theeye that may be reflected and detected by the camera. This “glint” pointremains substantially stationary since the camera 830 is fixed to theframe 812.

In addition, the video signals from a remote camera that may view theuser's face from a distance may be used to monitor various facialmeasures, such as facial expression, yawning frequency, and the like, inaddition to or alternatively, the project instead of the projected lightreference frame from the emitters. In addition or alternatively, theparameters from other sensors may be processed and correlated, such ashead orientation, tilt, body movement, physiological parameters, and thelike. Preferably, the processor may correlate these parameters togenerate a composite fatigue index (CFI) that is a function of two ormore of these parameters. When a predetermined CFI is detected, thesystem 810 may activate an alarm or other notice to the user and/or toanother party at a remote location. Thus, the system 810 may provide amore effective way to monitor the user's fatigue, drowsiness, alertness,mental state, and the like. In a further alternative, the system 810 maybe used to generate predetermined outputs, e.g., to activate ordeactivate equipment, such as a vehicle being operated by the user whena predetermined condition, e.g., CFI value, is determined by the system810.

Alternatively, the processor may be provided on the frame 812, e.g. aspart of processor 842, for monitoring the parameters for a predeterminedevent, such as a predetermined CFI value, to occur. Although only asingle lens and set of emitters, sensors, and cameras are shown, it willbe appreciated that another set may be provided for the other eye of theuser of the system 810. In a further alternative, the eye trackingparameters described above may be monitored by a remote camera, e.g., ina fixed position in front of the user, such as the dashboard of avehicle and the like. The remote camera may be coupled to the processor,either directly or via its own transmitter, as will be appreciated bythose skilled in the art.

Thus, a system in accordance with the present invention may monitor ordetect one or more parameters, such as those listed below in Table 1.

TABLE 1 Potential Biometric Measures EYELID MEASURES EYEGLAZE MEASURESPercentage of time (t) and Eye Tracking Movements (ETM) the amountpalpebral including Directional Nystagmus fissure is opened Eye GazeDistance (EGD) and (PEROP-t, -d, -dt), Direction or closed Eye MovementDistance (PERCLOS-t, -d, -dt), Eye Movement Velocity (EMV) lid droop EyeMovement Acceleration (EMA) Eye Blink Duration (EBD) and Deceleration(EMD) Eye Blink Frequency (EBF) Eye Movement Frequency (EMF) Eye BlinkVelocity (EBV) Phoria/eye Drift Measures (PDM) Eye Blink AccelerationHEAD ORIENTATION MEASURES (EBAc) Head Direction or OrientationDecceleration (EBDc) (HDir) Interblink duration (IBD) HEAD MOVEMENTMEASURES Eye blink flurries Head Nodding Frequency (HNF) PUPIL MEASURESHead Tilt (HT) Pupillary Appearance or OTHER NON- Disappearance (witheyelid VIDEO SENSOR METRICS movement) EEG, EKG, pulse, oxygen PupillarySize Measurement saturation, respiration rate, (PSM) body temp, skinconductance, Presence and quality of actigraphic movements, headPupillary lilt sensors Dilation or Construction (including Hippus)

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the appended claims.

1. A system for monitoring movement of a person's eye, comprising: a device configured to be worn on a person's head; an array of emitters on the device for directing light towards an eye of the person when the device is worn, the array of emitters configured for projecting a reference frame towards the eye; and a camera oriented towards the eye for monitoring movement of the eye relative to the reference frame; and one or more sensors on the device for detecting light from the array of emitters that is reflected off of the eye or its eyelid, the one or more sensors producing an output signal indicating when the eye is open or closed.
 2. The system of claim 1, wherein the one or more sensors comprise an array of sensors in a predetermined relationship with the array of emitters for detecting light from the array of emitters that is reflected off of respective portions of the eye or its eyelid, each sensor producing an output signal indicating when the respective portion of the eye is covered or not covered by the eyelid.
 3. The system of claim 1, wherein the array of emitters and the one or more sensors are disposed separately and substantially laterally from one another.
 4. The system of claim 1, wherein the array of emitters and the one or more sensors comprise solid state devices capable of operating both as an emitter and as a sensor.
 5. The system of claim 1, wherein the camera is configured for producing a video signal, and wherein the system further comprises a processor for correlating the output signal from the one or more sensors with the video signal from the camera for determining the person's level of drowsiness.
 6. The system of claim 5, further comprising a warning indicator on the device, the warning indicator being activated when the processor determines a predetermined level of drowsiness has occurred.
 7. The system of claim 1, wherein the array of emitters comprises a plurality of emitters disposed in a substantially vertical arrangement on the device.
 8. The system of claim 7, wherein the array of emitters further comprises a plurality of emitters disposed in a substantially horizontal arrangement on the device.
 9. The system of claim 1, wherein the array of emitters is configured for projecting a set of crossed bands towards the eye for dividing a region including the eye into four quadrants.
 10. The system of claim 1, further comprising a transmitter on the device for wireless transmission of video output signals from the camera to a remote location.
 11. The system of claim 1, wherein the array of emitters comprise infrared emitters configured to emit pulses of infrared light.
 12. The system of claim 11, wherein the camera comprises an infrared camera.
 13. The system of claim 1, wherein the camera is mounted on the device.
 14. The system of claim 13, wherein the camera comprises a fiberoptic assembly.
 15. The system of claim 13, wherein the camera comprises at least one of a CCD and CMOS detector.
 16. The system of claim 1, further comprising a sensor on the device for detecting one or more physiological characteristics of the person.
 17. The system of claim 16, wherein the sensor comprises at least one of an EEG electrode, an EKG electrode, an oximetry sensor, a pulse sensor, an airflow sensor, and a temperature sensor.
 18. The system of claim 1, further comprising at least one of an orientation sensor for detecting the spatial orientation of the device and an actigraphic sensor.
 19. The system of claim 1, wherein the device comprises at least one of an eyeglass frame, a hat, a helmet, a visor, and a mask.
 20. A system for monitoring movement of a person's eye, comprising: a frame configured to be worn on a person's head; an array of emitters on the frame for directing light towards an eye of the person when the frame is worn, the array emitters configured to project a reference frame towards the eye; an array of sensors on the frame in a predetermined relationship with the array of emitters for detecting light from the array of emitters that is reflected off of respective portions of the eye or its eyelid, each sensor producing an output signal indicating when the respective portion of the eye is covered or not covered by the eyelid; a camera on the frame for monitoring movement of the eye relative to the reference frame, the camera configured for producing a video signal of a region of the eye and the reference frame; and a transmitter coupled to the sensor for wireless transmission of the output signal and the video signal to a remote location.
 21. The system of claim 20, further comprising a processor for correlating the output signal and the video signal to determine the person's level of drowsiness.
 22. The system of claim 21, further comprising a display for providing a graphical output of the output signal simultaneous with the video signal.
 23. A method for monitoring movement of a person's eye using a detection device including an array of emitters that are directed towards an eye of the person when the detection device is worn, and a camera oriented towards the eye away from the person when the detection device is worn, the method comprising: emitting light from the array of one or more emitters towards the eye to project a reference frame onto the eye; monitoring movement of the eye relative to the reference frame the person's surroundings with the camera; and generating a graphical output of the movement monitored by the camera relative to the reference frame; wherein the detection device further comprises one or more sensors, and wherein the method further comprises detecting light from the array of one or more emitters reflected off of the eye with the one or more sensors, the one or more sensors producing a light intensity signal indicating when the eye is open or closed.
 24. The method of claim 23, wherein the array of sensors is disposed in a predetermined relationship with the array of one or more emitters for detecting light from the array of one or more emitters that is reflected off of respective portions of the eye or its eyelid, each sensor producing an output signal indicating when the respective portion of the eye is covered or not covered by the eyelid.
 25. The method of claim 24, further comprising correlating the output signal from the one or more sensors with video signals produced by the camera monitoring movement of the eye relative to the reference frame, thereby determining the person's level of alertness.
 26. The method of claim 23, wherein the monitoring step comprises measuring movement of the eye's pupil relative to the reference frame.
 27. The method of claim 26, further comprising graphically displaying the movement of the eye's pupil relative to the reference frame.
 28. The method of claim 25, further comprising providing a warning to the person when the determined level of alertness falls below a predetermined level.
 29. A system for monitoring movement of a person's eye, comprising: a device configured to be worn on a person's head such that the device does not interfere substantially with the person's vision along an axis extending directly ahead of a first eye of the person; one or more emitters on the device for directing light towards the first eye when the device is worn; an array of sensors on the device directed towards the first eye when the device is worn, the sensors configured for converting images of the first eye into output signals; and a processor coupled to the sensors for interpreting the output signals to control one or more devices, wherein the one or more emitters and the sensors are provided on the device at locations offset from the axis to generally minimize interference with the person's vision and such that the array of sensors are oriented directly towards the region surrounding the first eye.
 30. The system of claim 29, further comprising a control system communicating with the processor, the processor configured for directing the control system to control one or more devices based upon the output signals.
 31. The system of claim 29, further comprising a computer communicating with the processor, the processor configured for controlling the computer based upon the output signals.
 32. The system of claim 31, wherein the processor is configured to interpret the output signals to operate the computer as an eye-activated mouse.
 33. The system of claim 29, wherein the one or more emitters comprise a plurality of infrared emitters configured to emit pulses at a predetermined frequency.
 34. The system of claim 29, wherein the device comprises a frame comprising a bridge piece extending between a pair of ear supports, the bridge piece including a nose bridge configured to be placed on the person's nose, and wherein the array of sensors are provided on or adjacent the nose bridge lateral from the first eye when the frame is worn to generally minimize interference with the person's vision along the axis.
 35. The system of claim 34, wherein the one or more emitters comprise an array of emitters provided on the frame.
 36. The system of claim 29, wherein the device comprises a nose bridge configured to be placed on the person's nose, and wherein the array of sensors are provided on or adjacent the nose bridge lateral from the first eye when the device is worn to generally minimize interference with the person's vision along the axis.
 37. The system of claim 36, wherein the device comprises a mask.
 38. The system of claim 36, wherein the device comprises an eyeglass frame.
 39. A method for monitoring movement of a person's eye using a detection device including one or more emitters and an array of sensors that are directed towards a first eye of the person when the detection device is worn, the method comprising: placing the detection device on a person's head such that the detection device does not interfere substantially with the person's vision along an axis extending directly ahead of the first eye and the array of sensors are offset from the axis and oriented directly towards a region surrounding the first eye; emitting light from one or more emitters towards the first eye; detecting light from the one or more emitters reflected off of the first eye with the array of sensors, the array of sensors producing light intensity signals indicating when the first eye is open or closed; and interpreting the light intensity signals to control one or more devices.
 40. The method of claim 39, wherein the array of sensors comprises a two-dimensional array of sensors.
 41. The method of claim 39, wherein the light intensity signals are used to control a computer.
 42. A system for controlling a computing device, comprising: a frame configured to be worn on a person's head such that the frame does not interfere substantially with the person's vision along an axis extending directly ahead of a first eye of the person; a sensor on the frame comprising a lens offset from the axis and oriented directly towards the region surrounding the first eye when the frame is worn, the sensor generating output signals representing video images of the first eye; and a processor coupled to the sensor for processing the output signals to monitor movement of the first eye relative to a reference frame, the processor communicating with an electronic device remote from the frame and interpreting the output signals to control the electronic device.
 43. The system of claim 42, wherein the sensor comprises a detector coupled to the lens by a fiberoptic cable.
 44. The system of claim 42, wherein the electronic device comprises a computer, and wherein the processor is configured to interpret the output signals to operate the computer as an eye-activated mouse.
 45. The system of claim 42, wherein the frame comprises a bridge piece extending between a pair of ear supports, the bridge piece including a nose bridge configured to be placed on the person's nose, the sensor provided on or adjacent the nose bridge at a location lateral from the first eye when the frame is worn to generally minimize interference with the person's vision along the axis.
 46. The system of claim 42, further comprising a plurality of infrared emitters on the frame for directing light towards the first eye of the person when the frame is worn, the emitters configured to emit pulses at a predetermined frequency.
 47. The system of claim 46, wherein the emitters are configured for projecting the reference frame onto the first eye of the person wearing the frame.
 48. A system for controlling a computing device, comprising: a frame configured to be worn on a person's head such that the device does not interfere substantially with the person's vision; a sensor on the frame comprising a lens directed towards the eye of the person when the frame is worn, the sensor generating output signals representing video images of the eye; and a processor coupled to the sensor for processing the output signals to monitor movement of the eye relative to a reference frame, the processor communicating with an electronic device remote from the frame and interpreting the output signals to control the electronic device, wherein the processor is configured for monitoring the output signals to detect video images indicating that the person wearing the device has blinked in a predetermined sequence, the processor configured for executing the command on the electronic device based upon the predetermined sequence.
 49. A system for monitoring movement of a person's eye, comprising: an eyeglass frame comprising a nose bridge configured to be placed on the person's nose, and a pair of ear supports configured to be placed over the person's ears such that the frame, when worn on the person's head, does not interfere substantially with the person's vision along an axis extending directly ahead of a first eye of the person; one or more emitters on the frame for directing light towards the first eye when the frame is worn, the one or more emitters provided on the frame at one or more locations that generally minimize interference with the person's vision along the axis; a sensor on or adjacent the nose bridge such that the sensor is offset from the axis to generally minimize interference with the person's vision along the axis and oriented directly towards the region surrounding the first eye, the sensor configured for converting images of the first eye into output signals; and a processor coupled to the sensor for interpreting the output signals to control one or more devices.
 50. The system of claim 49, wherein the sensor comprises a lens oriented directly towards the region surrounding the first eye when the frame is worn, and a detector coupled to the lens for converting the images of the first eye into digital video signals comprising the output signals.
 51. The system of claim 49, wherein the one or more devices comprise a computer.
 52. The system of claim 49, wherein the one or more devices comprise a wheelchair. 